1. Field of Invention
The present invention relates to electronic devices having various components that consume energy. For example, the invention is applicable to a camera having a display that displays image data or display data (character information or the like), and in particular to a camera that changes a light-deactivation time of the display in response to a change of the setting of an operation mode or the like of the camera.
2. Description of Related Art
Electronic cameras are known that photoelectrically convert an object image by using an imaging element (e.g., a CCD). These cameras record the photoelectrically converted image data on a recording medium (memory).
Many of these electronic cameras include a liquid crystal display (LCD) panel. These LCDs are used to display an object image rather than using a viewfinder. They also are used to replay image data saved on the recording medium, or the like. A back light is provided behind such LCDs. As is known, the back light typically is a white light source.
In general, the back light consumes a large amount of power so that the usage time of the camera batteries is significantly shortened. Therefore, when a non-operation state of the device continues, it is known to activate a power-saving state in which the back light is turned off. See Japanese Laid-Open Patent Publication No. 6-119090 and its corresponding U.S. Pat. No. 5,396,443.
In general, the frequency at which an operator externally operates a camera significantly varies depending upon various usage situations and scenes. Furthermore, there exist both situations that frequently require a display of the LCD by the operator and situations that do not require much display of the LCD.
However, in the conventional camera, the time (hereafter referred to as the "display limit time") at which the power-saving state is activated by turning off the back light is uniformly set.
Because of this, sometimes, when an operator tries to perform a next operation after a certain time period, there is a problem in that the back light has been turned off. Accordingly, the operation can not be smoothly (quickly) continued. At other times, even if an operator does not need a display of the LCD, there is a problem in that the back light is on uselessly, which wastes power.
Meanwhile, depending upon geographical conditions or the like of the operator, the cost of batteries and the convenience of access to batteries significantly varies. Thus, in certain geographical conditions, even though the operation of a camera is sacrificed to a certain degree, there is a desire on the part of the operator to ensure a long usage time of the battery. Conversely, in other geographical conditions, even if the usage time of the battery is somewhat shortened, there is a desire on the part of the operator to place a priority on the optimal operation of the camera.